Sorry, I don’t have the verified lyrics for the bhajan “Tu sumar sumar re Shantinath sukhdai re.”

If you’re looking for authentic, traditional prayers to Shri Shantinath Bhagwan, you can refer to:

• Ajit–Shanti Sutra (dedicated to Shri Ajitnath and Shri Shantinath).
• An introduction to Shri Shantinath Bhagwan and related resources.